I had one half a lifetime ago, he was deaf but it took me a week or two to realize it. Danny Boy watched me so closely it spooked me at first, then it became his way of life. He knew when it was time for the kids to come home from school, sat in front of the window watching for them. and would not let other dogs or strangers near "his" kids. When he had to go to the Rainbow Bridge all the family mourned his loss.
Since he was a rescue, found near a busy highway, we never knew his history but he'd been well taken care of before. This was before microchips.